This penthouse apartment is in a waterfront complex in Gdynia, Poland, a port city on the Baltic Sea. It occupies the 31st floor of the taller of two structures that make up Sea Towers, one of the highest residential buildings in the country, at 466 feet.

Designed by Andrzej Kapuscik, an architect based in Vienna, it was built in 2009, as Gdynia was growing in popularity as a tourist destination. The building has an observation deck and a social room for residents on the top floor, as well as concierge services, said Pawel Laczynski, an agent with Poland Sotheby’s International Realty, which has the listing.

This 4,103-square-foot apartment, which has two bedrooms and with two and a half baths, is reached by a private elevator. It has two terraces, one with views of the city and the other overlooking the bay.

The unit has an open floor plan, with no walls separating the study, kitchen, dining area and living room. The floors are oak, and the light fixtures are from Cini & Nils, an Italian company. The living room has floor-to-ceiling windows, sofas from the German maker Rolf Benz and a Bang & Olufsen sound system. (The furniture and the art are included in the price, Mr. Laczynski said.)

The kitchen is in a corner of the apartment, with black matte granite countertops and cabinets from HTH, a Danish company. A large island includes double ovens, a plate warmer and an iron-plate cooking grill.

The master bedroom has an en-suite bathroom, as well as a whirlpool bathtub and shower in the middle of the room, which has a city view. The second bedroom, on the other side of the unit, also has an en-suite bathroom. There is a laundry room and a half-bathroom next to a room used as a study. The apartment includes three parking spaces in an underground garage, and the building has 24-hour security, Mr. Laczynski said.

Gdynia, which has a population of about 249,000, is part of a tri-city area that includes Sopot and Gdansk, one of the largest cities in Poland, with about 460,000 residents. The apartment is near Kosciuszko Square, a popular gathering spot, and is a short walk to the pier, theaters, restaurants and Swietojanska Street, the city’s main shopping area. Lech Walesa International Airport is about 13 miles away, in Gdansk.

MARKET OVERVIEW

Home sales in Poland are booming, said Aleksandra Galabuda, a consultant with REAS Residential Advisors in Warsaw.

In the country’s six main residential markets, including the tri-city area, the number of sales has been increasing by about 20 percent year over year since 2013, she said. That increase, agents said, can be attributed in part to low interest rates, declining unemployment and rising wages.

In Gdansk, an average of 2,000 homes were sold each quarter in the last 18 months, compared to 1,400 a quarter in 2015 and 1,200 in 2014, Ms. Galabuda said.

The tri-city area is one of the strongest markets in Poland, said Arkadiusz Wojciechowski, managing director of Poland Sotheby’s International. Tourism, the port and a growing business environment have made it popular with investors and second-home buyers, he said.

New developments are sought-after and often sell out quickly, especially on the waterfront, Mr. Wojciechowski said. The popularity of short-term rental sites like Airbnb has increased interest in waterfront apartments that can be easily rented, he said, adding that people “are buying because they feel it is a good investment.”

In Poland’s luxury market, the highest prices paid for second homes in 2016 were in Sopot, said Mikolaj Baca, regional director of the real estate agency Keller Williams Poland. Last year, sales prices there averaged 8,176 zlotys a square meter (about $211 a square foot), compared to 7,371 zlotys a square meter (or $190 a square foot), in Warsaw. And “forecasts for the next few years are even better,” he said.

WHO BUYS IN GDYNIA

The vast majority of buyers in the tri-city area are Polish, but the number of foreign buyers is growing, agents said. The largest groups are from nearby countries like Germany and Ukraine, Mr. Baca said, followed by those from Britain, France, Italy, Belarus, Russia and Sweden.

Mr. Wojciechowski said he is seeing more buyers from Scandinavia and “a small number” from Russia.

BUYING BASICS

Foreigners typically need a permit to buy land in Poland, although there are exceptions for different types of property and for European Union residents, agents said, particularly if a buyer has lived in Poland for more than five years or is married to a Polish national. Obtaining a permit usually takes less than two months, Mr. Wojciechowski said.

A notary handles the details of the sale, including registering it with the local land records. Although the process is not complicated, most buyers hire an adviser to help with the language and local regulations, Mr. Wojciechowski said. Mortgages are available to qualified foreign buyers, with interest rates as low as 3.5 to 4 percent, agents said.

Buyers are required to pay a transfer tax of 2 percent of the value of the property, agents said. Agents’ fees are typically 3 percent of the sale price. The cost of a notary depends on the price of the property, but cannot exceed 10,000 zlotys (or $2,800), which is about what it would be for this property, Mr. Wojciechowski said. Buyers can also expect to pay small fees for registration and translations — about 3,000 zlotys (or $830) for this home, Mr. Laczynski said.

The annual tax on this property is about 286 zlotys (or $80), Mr. Laczynski said. Building maintenance and homeowner association fees are about 5,000 zlotys (or about $1,400) a month, including basic utilities, he said.